Railway switch operating apparatus



April 20, 1943. H. 1.. BONE 2,316,930

RAILWAY SWITCH OPERATING APPARATUS Filed Nov. 15, 1941 4 Sheets-Sheet l IN VEN TOR 191 f L 50129 BY HIS ATTORNEY April 20, 1943. H. L. BONE 2,316,930

RAILWAY SWITCH OPERATING APPARATUS Filed Nov. 15, 1941 4 Sheets-Sheet 2 April 20, 1943. H. 1.. BONE RAILWAY SWITCH OPERATING APPARATUS Filed Nov. 15, 1941 4 Sheets-Sheet 3 HIS Aframm April 20, 1943. H. L. BONE 2,316,930

RAILWAY SWITCH OPERATING APPARATUS Filed Nov. 15, 1941 4 Sheets-Sheet 4 WM I i Her L Bone BY 1115 Ai'TORNEY Patented Apr. 20, 1943 RAILWAY SWITCH OPERATING APPARATUS Herbert L. l sone, Forest Hills, Pa., assignor to The Union Switch & Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application November 15, 1941, Serial No. 419,343

3 Claims.

My invention relates to railway switch operating apparatus, and particularly to apparatus for operating spring switches.

One object of'my invention is to provide means for decreasing the pressure which the points of a spring switch exert against the wheels of a car while a train is trailing the switch, without de- I creasing the force which is effective for holding the switch points in either of their extreme positions when they are moved to such extreme positions by the switch operating means, thus materially reducing the wear on the switch points and hence increasing the life of the switch.

Another object of my invention is to provide improved means for decreasing the slapping of the points of a spring switch during trailing moves over the switch.

According to my invention, a toggle spring unit and a pair of oil buffer cylinders are operatively connected, within a single housing, with a crank which is connected to the switch, and which rotates in response to movement of the switch from either extreme position to the other. The toggle spring is adapted to function in cooperation with the usual spring head rod, and is so arranged that it will bias the switch to its nearest extreme position with a force which is somewhat less than that exerted on the switch at any time by the spring head rod, whereby when the switch occupies its normal set position, it is biased to this position by the combined forces exerted by the toggle spring and the spring head rod, but that, when the switch is trailed the force of the toggle spring opposes that due to the spring head rod and thus decreases the force which the switch exerts against the wheels of the trailing train. The oil buffer cylinders include valves so operated by operation of the switch operating device that free movement of the switch from either extreme position to the other is permitted either when the switch is operated by the switch operating device or when it is trailed by a trailing train, but that, the return movement of the switch rails to their set positions after the switch is trailed by a train is retarded by the action of one or the other of the buffercylinders depending upon whether the switch initially occupies its normal or its reverse position.

Other objects and characteristic features of my invention will become apparent as the description proceeds.

My present invention is an improvement upon that shown in my prior Patent No. 2,061,752 granted November 24, 1936, for Railway switch operating apparatus.

In the accompanying drawings, Fig. 1 is a top plan view partly in cross section, showing a spring switch provided with one form of switch operating apparatus embodying my invention. Fig. 2 is top plan view of the device Dforming-part of the apparatus illustrated in Fig. 1, and embodying my invention, the cover for the casing being removedand some of the parts being shown in section to better illustrate the construction and arrangement of the remaining parts. Fig. 3 is a view, partly in front elevation and partly in section of the device D shown in Fig. 2. Fig. 4 is a sectional view taken substantially on the line IV-IV of Fig. 2 but with the parts in a different position from that in which they are shown in Fig. 2. Fig. 5 is a sectional view taken substantially on the line V--V of Fig. 3.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference character A designates a railway switch, and the reference character B designates a device for operating the switch A. The switch A comprises as usual two fixed rails l and la and two movable switch points 2 and 2a, the switch points being connected together adjacent their tips by a head rod 3.

The operating device B, as here shown, comprises a switch stand 4 having its base 4a spiked or otherwise secured to the ties adjacent the switch A. A gear shaft 6 is journaled in the switch stand 4 and carries a crank 5 and a gear segment I. The gear segment 1 meshes with a pinion gear 8, keyed to a pinion shaft 9. The pinion shaft 9 extends through the side of the switch stand 4 and has attached to its outer end the usual weighted switch throwing lever Ill.

The crank 5 of the switch throwing device B is connected with the head rod 3 of switch A by means of a link H and a spring connecting red C. The spring connecting rod C may have any suitable form, but in the Well-known form here shown, this connecting rod comprises a cylindrical housing l4 having a lateral extension Ma fastened to the head rod. 3. The right-hand end lob of the housing I4 has a smaller diameter than the body of the housing, while the lefthand end is threaded to receive a cap I5 having an end lBa similar to the end Mb. Slidably mounted in the opening in the end l 41) is a sleeve It provided with an annular flange lfia located within the housing l4, and similarly mounted in the opening in the end 15a is a sleeve ll provided with an annular flange Ila located within the housing M. A spring rod I2 extends through both sleeves l6 and I! with sufllcient clearance to permit the rod to slidefreely in the sleeve, and this rod carries a compression spring I 3 which engages the sleeves at the annular flanges and urges the sleeves toward the positions in which the annular flange lie on the sleeve I6 engages the shoulder formed on the inside of the housing [4 by the end I41), and the annular flange IIa of the sleeve l1 engages the shoulder formed on the inside of the cap |5 by the end |5a. The

spring rod I2 i provided with an annular shoulder |3 for at times engaging the outer end of the sleeve l6, and with a nut l3 for at times engaging the outer end of the sleeve H. The right-hand end of the spring rod I2 is operatively connected with the crank 5 through the medium of a link The apparatus thus far described is well known, and its operation will be made clear as the description proceeds.

Associated with the switch A, the switch operating device B and the switch connecting rod C is a combined biasing and bufling device D embodying my invention. The device D is secured to the same crossties which support the switch operating device B on the side of the switch opposite to the device B, and as best seen in Figs. 2, 3 and 4, the device D in the form here shown comprises a main housing 20 provided with a reswitch A between its two extreme positions will rotate the crank shaft 24 between two extreme positions spaced substantially 90 apart. To prevent the escape of oil from the housing 20, the crank shaft 24 where it passes through the bottom wall of the housing is surrounded by a suitable packing gland 28.

into aligned buiier cylinders 38 and 39 formed in the auxiliary housings 22 and 23, and is secured to reciprocable pistons 40 and 4| disposed within the cylinders 38 and 39. The cylinders 38 and 33 are closed at their outer ends by cylinder heads 42 and 43 formed integrally with the auxiliary'housings 22 and 23, and communicate freely at their inner ends with the interior of the The crank shaft 24 is biased to its nearest extreme position by means of toggle mechanism comprising a toggle crank 29 and a toggle spring unit U. The toggle crank 23 is secured to the shaft 24 between the bearings 25 and 26, and is provided with an arm 29a and a segmental gear 292).

The toggle spring unit U comprises a spring sleeve 30 which is mounted to slide on one end of a spring rod 3|. The spring sleeve and spring rod are provided with spaced confronting annular flanges 30a and 3|a, respectively, and are surrounded between the flanges by two concentric compressed coil springs 32 and 33. One end of the toggle spring unit U i fulcrumed against the side wall of the main housing 20 directly opposite the main crank shaft 24 by means of a rounded portion 3|b provided on the outer end of the spring rod and fitting within a rounded socket 201) cast integrally with the main housing 20, and the other end of the toggle spring unit is pivotally attached to the arm 29a of the toggle crank 29 by means of a pin 34. The pin 34 extends through the arm 29a, and through the upper one of two spaced lugs 30b and 300 provided on the sleeve 30, and is screwed ,at its lower end into a tapped hole formed in the lug 300. The parts are so proportioned that the toggle mechanism will occupy its dead center position main housing 20.

A leak groove 44 is formed in the top wall of the cylinder 35 adjacent its right hand end, as viewed in Fig. 3, and a similar leak groove 45 is formed in the top wall of the cylinder 39 adjacent its left-hand end, as viewed in Fig. 3. The cylinders and the main housing are all intended to be filled with a suitable fluid such as oil, and the function of the grooves 44 and 45 is to permit fluid to flow past the pistons 40 and 4| under certain conditions which will be made clear hereinafter. To facilitate inserting fluid into the device, a filling plug 46 is provided in the cover .2 I, as shown in Fig. 4.

The right-handlend of the cylinder 38 is connected with the interior of the main housing and attached to a valve stem 5|b. The valve member 5|a is provided with a pluralityof restricted orifices 5|c of different sizes, any one of which may be brought into registration with the port 52 by turning the valve member 5|a. To facilitate turning the valve member, the valve stem 5|b is provided in its upper end with a saw kerf 5|d adapted to receive the end of a screw driver. The valve 5| is held in place by a gland 55 which surrounds the valve stem 5| b, and which is fastened to the cylinder head 42 by means of two stud bolts 55 that pass through suitable holes in the gland and are screwed into threaded holes (not shown) in the cylinder head 42.- Suitable packing 51 is inserted between the gland 55 and a shoulder formed at the top of the valve member 5| a to prevent fluid from leaking past the valve. The right-hand end of the cylinder 33 is also connected with the interior of the main housing through a poppet valve 58, a port 59 and the passageway 53. The poppet valve 58 is formed with a fluted valve stem 58a which extends through the port 59, and with a spring guide 58b, and seats against a valve seat 60 formed in the right-hand end of the port 59. One end of a compressed spring 5| engages the valve around the spring guide 58b, and constantly urges the valve to the position in which it seats against the valve seat ill. The other end of the spring 6| extends into an annular recess 52 formed in a plug 53' screwed into a threaded opening in the cylinder head 42. The plug 53 is made sufllciently large to permit ready insertion and removal of the valve 53 and its associated parts.-

The left-hand end of the cylinder 33 is connected with the interior of the main housing 23 through a port 35, a timing valve 66, a port i1, and a passageway 53 that extends parallel to the cylinder at one side of the cylinder. The timing valve 88 is similar to the timing valve andis mounted in the cylinder head 43 in the same manner that the valve 5| is mounted in the cylinder head 42. Since the valve 88 is similar to the valve 5|, and is similarly mounted, it is believed that further detailed description of this valve is unnecessary.

The left-hand end of the cylinder 38 is also connected with the interior of the main housing 20 through a poppet valve 69, a port 10. and the passageway 68. This latter valve is similar in all respects to the poppet valve 58, and its construction will be apparent from an inspection of the drawing without further detailed description. The poppet valve 58 is operated by a cam 75 through the medium of two push rods 18 and II, and the poppet valve 69 is similarly operated by the cam through the medium of two push rods 18 and 19. The cam 15 is substantially oval shaped, and is mounted on a cam shaft 80 journaled in a bearing 8| formed in the cover 2| at one side of the main crank shaft 26. The cam shaft 88 extends upwardly through the cover 2|, and is provided at its upper end with a crank arm 33. -This crank arm is connected with the spring rod ll of the spring connecting rod C by means of an adjustable link 8i. Downward movement of the cam shaft 88 due to the weight of the link 84 and the crank arm 83 is resisted by a pointed thrust bearing 82 formed on the lower end of the cam shaft, while leakage of oil past .the cam shaft is prevented by a suitable packing gland 85.

The push rod 18 is slldably supported in guide lugs 88 and 81 cast on the side wall of the main housing 20, and cooperates at one end with the cam I5. The other end of this push rod is provided with a depending portion 16a which engages one end of the push rod TI. The push rod Tl is slidably supported in the bottom of the passageway 53 by means of guide lugs 88 and 89, and is constantly biased in the direction to maintain it in engagement with the push rod 16, and the push rod 16 in engagement with the cam 15 by means of a compressed coil spring 90 which surrounds the push rod ll between the guide lug 89 and a shoulder 'i'la formed on the push rod.

The push rod 18 is slidably mounted in guide lugs 8| and 92 cast in the side wall of the main housing 2|, and cooperates at one end with the cam E5. The other end of this push rod is provided with a depending portion 180. which engages one end of the push rod 19. The push rod 19 is slidably supported in guide lugs 93 and 94 formed in the bottom of the passageway 88, and is constantly biased in the direction to maintain it in engagement with the push rod 18, and the push rod 18 in engagement with the cam I5, by means of a compressed coil spring 95 which surrounds the push rod between the guide lug 93 and a shoulder 79a formed on the push rod.

In explaining the operation of the apparatus as a whole, I shall assume that the parts are all in their normal positions in which they are shown in the drawings, and that it is desired to move the switch points from their normal to their reverse positions. To do this, the hand throw lever l8 of the switch throwing device B is rotated from the position shown through an angle of 180 in a clockwise direction, thereby rotating gear seg ment 1 and crank 5 in the same direction, and hence moving link II and spring rod l2 toward the left. The motion of the spring rod l2 toward the left causes a force to be exerted on the switch points 2 and 2a through the medium of the annular shoulder l3, sleeve l8, spring l8, sleeve l1, end cap l5, housing l4, and head rod 3, which force moves the switch points to their reverse positions.

During the movement of the switch points to their reverse positions, the crank shaft 24 due to its connection with the head rod 3, is rotated in a clockwise direction, as viewed in Fig. 2, and the cam shaft due to its connection with the spring rod I2 is also rotated in a clockwise direction as viewed in Fig. 2.

The rotation of the crank shaft 24 actuates the toggle spring unit U from the extreme position shown in Fig. 2 to its opposite extreme position, and it will be apparent, therefore, that during the first half of the movement of the switch points to their reverse positions, the toggle spring unit will exert a force on the switch points which opposes their motion, but that, during the second half of the movement of the switch points to their reverse positions, the toggle spring unit U will then exert a force on the switch points which aids their movement. It will also be apparent that the force which is exerted on the switch points by the toggle spring unit U opposing their movement to their reverse positions will decrease as the switch points approach their mid stroke positions, while the force which is exerted on the switch points by the toggle spring unit aiding the movement of the switch points to their reverse positions will increase as the points move away from their mid stroke positions.

It will further be apparent that in order to avoid excessive deflection of the spring IQ of the spring connecting rod C, this spring should be made sufficiently stiff to exert a somewhat greater force on the points at the beginning of their movement toward their reverse positions, than is exerted on the points by the toggle spring unit.

The clockwise rotation of the crank 24 also acts through the medium of the segmental gear 291) and the rod 31 to move the pistons 40 and 4| toward the right within'the associated cylinders 38 and 39 from one end of their stroke to the other. The cam 75 is so shaped, and the parts are so proportioned, that during this movement of the pistons 40 and 4|, valve 58 will be held open until after the piston 40 has passed the lefthand end of leak groove 44, and valve 59 will be opened as soon as the piston 4| has reached the right-hand end of the leak groove 45. As a result, during this movement of the pistons 40 and 4| fluid flows from cylinder 38 on the right-hand side of piston Aid past valve 58 and through passageway 53 into the main casing 20, and from thence into cylinder 38 on the left-hand 'side of piston 40, until piston 48 passes the left-hand end of leak groove 44 as viewed in Fig. 2, whereupon valve 58 closes, and fluid in the right-hand side of piston 60 thereafter flows through leak groove 54 into cylinder 38 on the left-hand side of -piston fill. During this movement, fluid also flows from cylinder 39 on the right-hand side of piston 4| through leak groove 45 into cylinder 39 on the left-hand side of piston 4| until piston 4| passes the right-hand end of leak groove 45, whereupon valve 59 opens and fluid then flows into cylinder 39 on the left-hand side of piston 4| from the main housing 20 through passageway 58 and port I0. It will be apparent, therefore, that during the movement of the switch A ,from its normal to its reverse position by the switch operating device B, the fluid in the device D offers tion, the switch is returned to its normal position 5 by the switch operating device D, the operation of the apparatus will be just the reverse of that described above, and it is accordingly-believed that this operation will be readily understood from the foregoing description and from an inw spection of the drawings without further detailed description.

I shall now assume that the parts are in their normal positions as shown in the drawings, and that a train trails the switch. Under these conditions, as the wheels of the train roll along the fixed rail l and the movable switch point 2a, the switch points 2 and 2a will be forced toward their reverse positions by the wheels, and since spring rod I2 is now held stationary by virtue of its connection with the switch operating device B, spring II will become compressed and will exert an increased force on the switch points tending to restore them to their normal positions. The movement of the switch points toward their reverse positions will also cause the main crank 24 of the device D to be rotated in a clockwise direction as viewed in Fig. 2, in the same manner as when the switch was moved to its reverse position by the switch operating device D, with the result that while the switch points are being moved to their mid stroke position the toggle spring unit U will exert a force on the points which aids that exerted on the points by the spring l9 of the spring connecting rod C in tending to restore the points to their normal positions, but that, as soon as the switch points have been moved past their mid stroke positions, the toggle spring unit U will then exert a force on the points which opposes that exerted on the points by the spring l9. and which tends to move the points toward their reverse positions. The stiffness of the springs i9 is such, and the parts are so proportioned that the force which is exerted on the switch points by the spring I9 under these conditions will always be greater than that exerted on the points by the toggle spring unit U,'but that, the resultant force which is exerted on the switch points under these conditions tending to restore the points to their normal positions will decrease as the points are moved away from their normal positions by an amount which is substantially proportional to the displacement of the points.

The clockwise rotation of the crank 21 in addition to operating the toggle unit U, acts through the segment gear 29b and rack 31 to move the pistons 40 and 4| from the extreme position shown to their opposite extreme positions. During this movement, 'cam shaft 90 due to its connection with the spring rod 12, is held stationary, and valve 59 therefore remains open. The fluid in the cylinder 99 on the right-hand side of piston 40 therefore flows through valve 99 and passageway 53 into the main casing 20 I until piston 49 has moved past the left-hand end of leak groove 44, whereupon fluid then also flows past piston 40 through this leak groove. The fluid in cylinder 99 on the right-hand side of piston 4| during this movement flows through leak groove 49 past piston 4i into cylinder 39 on the left-hand side of-piston ll until piston ll has moved to the end of this groove, whereupon the suction created in the left-hand end of cylinder 9! opens valve 99 and permits fluid relatively small. so that very little pressure is res quired to open valve 99. It will be apparent, therefore, that the buffer cylinders of the device D offer very little resistance to the movement of the switch points away from their initial posi- V tions under these conditions. As soon, however, as the switch points start to return to their initial positions due to the bias the spring connecting rod C, the spring associated with valve 99 together with the pressure of the fluid exerted on this valve closes this valve, so that fluid cannot pass this valve, and the return movement of the switch points is then limited to the rate at which the fluid in cylinder 99 on the left-hand side of piston ll as viewed in Fig. 2 can flow through the timing valve 99, until piston II has moved past the end of leak groove 45. This rate may be varied by varying the setting of the timing valve 99 to change the size of the orifice which is in registration with port .1, and this rate is usually adjusted so that the switch points will not return to their mid stroke positions under the action of the spring l9 of the spring connecting rod C until a time interval has elapsed which is longer than the time interval required for adjacent trucks of a car to pass the switch points when the train is moving at the usual trailing speeds. As the switch points move toward their mid stroke positions,

toggle spring unit U moves toward its dead cen-- ter position, thus reducing the effect of the toggle spring unit U in holding the switchpoints open. When the switch points reach their mid stroke positions, piston ll clears the left-hand end of leak groove 49 thus allowing the oil to flow freely from the left-hand side of piston 4| through the groove to the right-hand side, and hence relieving the bufling action, whereupon the switch is returned rapidly to its normal position by the combined action of the toggle spring unit U and the spring connecting rod C. When the switch points have been restored to their full normal positions, all parts are then restored to their normal positions in which they are shown in the drawings.

When the switch occupies its reverse position, 50

be seen that if a train trails the switch under these conditions the switch points will move toward their normal positions with substantially no resistance due to the buffer cylinders. However, since valve 59 is now closed, when the switch points start to return to their normal positions, the fluid in the right-hand end of cylinder 39 will be forced to flow through the timingyalve 5| until piston 49 passes the lefthand end of leak 60 groove 44, whereupon fluid can flow freely through the leak groove. The rate at which fluid can flow through the valve 5|, and hence therate of return of the switch points toward their initial positions may be varied by adjusting the valve 5|, 55 as will be readily understood from the foregoing description. The operation of the apparatus as a whole when the switch occupies its reverse position and a train trails the switch is similar to that described above when the switch occupies its normal position and a train trails the switch and a detailed description of this operation is accordingly believed to be unnecessary.

It should be particularly pointed out that with the apparatus constructed in the manner just valve 69 is open and valve 58 is closed, and it will' described. thespring l9 0! the spring connecting rod C, and the springs of the toggle unit U will preferably be so constructed and the parts will be so proportioned that the total force which is exerted on the switch points by these springs when the switch points are moved to either their normal or their reverse positions by the switch operating device B will be equal to that customarily provided under similar conditions in spring switches as they have heretofore been constructed, and that, with the parts constructed and proportioned in this manner, the force which is exerted on the points tending to restore them to their original extreme positions when they have been moved away from such position by a trailing train will be only a fraction of that exerted on the points in the prior types of spring switches. For example, in the prior types of spring switches the force which is exerted on the switch points by the spring of the spring connecting rod'tending to hold the points in either extreme position when they have been moved to such extreme posltion by the switch operating device is usually one thousand pounds, and when a train trails the switch this force usually increases to two thousand pounds. With apparatus embodying my invention, however, assuming that when the switch points are moved to either extreme position by the device B, a force of six hundred pounds is exerted on the switch points by the spring IQ of the spring connecting rod and a force of four hundred pounds by the springs of the toggle spring unit U, and that the force which is exerted on the points by the spring IQ of the spring connecting rod when a train trails the switch increases to nine hundred pounds, then the force which is normally exerted on the points will be the same as in prior types of spring switches, but the force which is exerted on the points while a train is trailing the switch will be nine hundred .minus four hundred, or five hundred pounds, which latter force is only one-fourth of that which is exerted on the points under like conditions with the prior types of spring switches. It follows that with apparatus embodying my invention the wear on the switch points will be much less than in the prior types of spring switches.

It should also be pointed out that in the prior types of spring switches in which buffing devices are provided, there is a certain amount of kickback of the switch points before the buifing action becomes effective. This kick-back is due to the reversal of the parts, and occurs partly in the boiling device itself and partly in the connections between the bufiing device and the switch points. With apparatus constructed in accordance with my present invention, the position of the toggle spring in either trailed position of the switch takes up the lost motion in the-connections between the buffer and the switch, thus eliminating the amount of the buffer kick-back which would ordinarily result from lost motion in any of the connections.

It should also be pointed out that the poppet valves 58 and 69 are located close to, but not right on the bottom of the buffer, which is an advantage because there is less likelihood for them to trap air, which would be the case if they were near the top, or the picking up of sediment or foreign matter if they were near the bottom.

It should further be pointed out that with the apparatus constructed in the manner" .-described there are no packed parts in the regions where high fluid pressures are developed; As a result,

fluid leakage is reduced to a minimum and a higher head of oil can be maintained for a longer period of time than is possible with designs in which packed parts are subjected to the high fluid pressures which are developed between the pistons and the cylinder heads when a train trails the switch.

It should also be noted that with apparatus constructed in accordance with my invention, the oil passages through which the oil flows when the device D is operated from one position to the other are ample in size and are also located at the same desirable elevation as the poppet valve, and

that a bafile Hit is provided between the air chamber of the oil buffer and the main oil compartment. Both of these arrangements tend to prevent excessive turbulence and the possibility of entraining air in the oil, and thus insure that a solid body of oil fills back of the bufier piston. Both the timing valves and the poppet valves are removable for cleaning and inspection without dismantling the buffer.

Although I have herein shown and described only one form of railway switch operating apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. The combination with a railway switch and an operating device connected with the switch by spring means which is efiective to bias the switch to either extreme position to which it is moved by said device, of a fixed housing, a crank shaft journaled in said housing and connected with the switch points, a toggle spring unit in said housing connected with said crank shaft and acting to bias the switch points to their nearest extreme positions with a force which is less than the force exerted on the points by said spring means, two buffer cylinders secured to said housing, two pistons one in each buffer cylinder, means including a rack attached to said pistons and meshing with a segment gear mounted on said crank shaft for operatively connecting said pistons with said crank shaft, and valve means associated with each buiTer cylinder so arranged that neither piston will oppose movement of said switch points by said operating device but that one piston or the other will act to retard the movement of the switch points toward their initial positions when a train trails the switch depending upon whether the points initially occupy their normal or their reverse positions.

2. In combination, a railway switch comprising a pair of switch points, spring means operatively connected with the switch points for yieldably resisting movement of the points in opposite directions by a train trailing through the switch and for returning the switch points to their original positions after the train has passed through the switch, a main housing fixed in the trackway adjacent the switch points, a crank shaft journaled in said main housing and operatlvely connected with the switch points, a toggle spring unit pivotally connected at one end to a crank arm secured to said crank shaft and fulcrumed at the other end against the side wall of said main I housing for biasing the switch points to their nearest extreme positions, whereby when the switch points are moved from either extreme position past their midstroke position by a trailing train said toggle spring unit will exert a force on total force urging the switch points toward their original positions, two auxiliary housings se. cured to said main housing and each formed with a cylinder which aligns axially with the cylinder in the other housing, a reciprocable piston in 'each cylinder, a rack connecting said pistons, a segment gear secured to said crank shaft and. meshing with said rack, said housings being filled with afluid, and valve means associated with each cylinder and selectively controlled in accordance with the set position of the switch points in such manner that the fluid in the one cylinder will act to prevent rapid movement of the associated piston and thus retard the return movement of the switch points toward one extreme position when and only when the switch points have been moved away from such position by a trailing train and that the fluid in the other cylinder will act to prevent rapid movement of the associated piston and thus retard the return movement of the switch points toward the other extreme position when and only when the switch points have been moved away fromsuch other position by a trailing train. 7

3. In combination, a railway switch comprising a pair of switch points connected by a head rod and movable between two extreme positions, a switch operating device movable between two extreme positions, means including a spring connecting rod for connecting said device with said head rod, the combination with the aforementioned instrumentalities, of a biasing and bufflng device comprising a main housing fixed in the trackway adjacent the switch points, a main crank shaft Journaled in said main housing and operatively connected with the switch points, a

.toggle spring ,unit pivotally connected at one end to a crank arm flxed to said main crank shaft and fulcrumed at the other end in a socket formed in the wall of said housing, the parts being so arranged that said toggle unit biases the -6 a,s1e,aso the switch points which acts to decrease the switch points to their nearest extreme positions with a forcewhich is somewhat less than that.

exerted on the points by. said springconnecting rod, two auxiliary housings secured toopposite sides of said main housing and each formed with a cylinder which aligns axially with the cylinder in the other auxiliary housing and with a passageway which extends parallel to the associated cylinder and which communicates at one end with the interior of said main housing, two timing valves one connecting the end of each cylinder which is farthest from said main housing with said passageway, two poppet valves one connecting the end of each cylinder which is farthest from saidmain housing with said passageway, said poppet valves being biased to closed positions, two pistons one reciprocable in each cylin der, a rack connecting said pistons, a segment gear secured to said main crank shaft and meshing with said rack, fluid disposed in said housings, means at the end of each cylinder farthest from said main housing for permitting fluid to leak past the associated piston for a portion of its stroke, a cam shaft Journaled in said main housing, a cam on said cam shaft, push rods operatively connecting said poppet valves with said cam shaft, and means connecting said cam shaft with said switch operating device, the parts being so proportioned that the fluid in'either cylinder is free to flow from either end of the cylinder to the other through said poppet valves or said leak groove when said switch is operated by said switch operating device or when the switch points are moved away from either extreme position by a trailing train but that one poppet valve or the other will close and force fluid to flow through one or the other of said timing valves to retard the movement of the switch points when the switch points are being returned toward either extreme position by said spring connecting rod HERBERT L. BONE. 

